<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{padding: 0;margin: 0;box-sizing: border-box;}
        .box{
            width: 400px;
            margin: 100px auto 0;
            background-color: #ddd;
            display: flex;
            -justify-content: flex-start;
            -justify-content: flex-end;
            -justify-content: center;
            -justify-content: space-between;
            justify-content: space-around;

        }
        .item{
            height: 30px;
            background-color: #f40;
        }
        .item:first-child{
            width: 70px;
            margin-right: 10px;
        }
        .item:nth-child(2){
            width: 30px;
            margin-right: 10px;
        }
        .item:nth-child(3){
            width: 120px;
        }
    </style>
</head>
<body>
    <div class="box">
        <div class="item">1</div>
        <div class="item">2</div>
        <div class="item">3</div>
    </div>
</body>
</html>